In the midst of recruiting subjects for a genetic study on perfect (absolute) pitch—the ability to discern a note from nearly any sort of sound without a reference tone—scientists at the University of California, San Francisco, discovered several interesting patterns among people who have the skill.

Among the findings of the study published this week in Proceedings of the National Academy of Sciences USA : "Either you've got it or you don't," says senior report author Jane Gitschier, a professor of medicine and pediatrics at U.C.S.F. She says that data collected from more than 2,000 people aged eight to 70 years old during the study indicates that there is likely a genetic basis to perfect pitch—one she believes is activated by early music training "Absolute pitch almost certainly requires exposure to music at a young age," Gitschier notes. "You need to have some idea of the nomenclature."

A total of 2,213 individuals took an online exam consisting of 36 electronic tones and 36 piano tones. For each sound they had to identify the corresponding note on the musical scale. A score of at least 24.5 on both tests indicated that a participant might have perfect pitch. To the researcher's surprise, there were two distinct clusters of results: "those that represent highly accurate pitch perception," the researchers wrote in the study, and those whose scores seemed to indicate that they were randomly guessing. From this striking dichotomy of haves and have-nots, Gitschier says, "Our data suggest that it could potentially be described by a single gene."

According to Gitschier, the data also supports anecdotal evidence from people that, as they get older, they experience a shift in pitch-naming ability. Apparently, several of the older participants were consistently shifting to sharp in their categorizations, labeling D as D-sharp or A-sharp as B. Gitschier surmises that the culprit may be the aging basilar membrane, the vibrating part of the cochlea (auditory component of the inner ear), which transmits information to the auditory cortex via hair cells on its surface and increases in elasticity over time.

Another finding, she says, was the all-too-common mistake that many study participants with absolute pitch made of miscategorizing tones—specifically, identifying G-sharp as an A. Gitschier explains that those who have perfect pitch essentially have ranges of acoustic frequencies in "bins" corresponding to different notes. This mistake may be attributable to the aforementioned shift toward perceiving notes sharper than they actually are. Or, rather, Gitschier says, because the note A is a universal tuning note for most instruments, "maybe people have learned to not consciously accommodate a wider range of frequencies and bin them as A."

From this study, the researchers plan to cull 100 to 200 of those who tested as having perfect pitch, provided they have a relative other than a parent who also has the ability. Each of these pairs will submit to a blood test that will allow the team to sequence their DNA and determine if there truly is a genetic underpinning for absolute pitch.

Gitschier says she would not be surprised if a single gene sits at the controls of absolute pitch, but she stresses that it is not all nature. "We know environment is a factor," she notes. "Somebody may have a genetic predisposition, but if they didn't have any early musical training, they may be out of luck."